Process for producing zinc lithographic plates.



CHARLES G. MEYN, OF ROCHESTER, NEW YORK.

PROCESS FOR PRODUCING ZINC LITHOGRAPHIC PLATES.

Specification of Letters Patent.

Patented Dec. 11, 1906.

Application filed March 9, 1906. Serial No. 305,077.

To all w/wm, it Huey concern:

Be it known that 1, CHARLES G. MEYN, a citizen of the United States,anda resident of Rochester, in the county of Monroe and St ate of- NewYork, have invent ed certain new and Y useful Improvements in Processesfor Producing Zinc Lithographic Plates, of which the following is aspecification.

This invention relates to the production of surfaces on zinc plates forlithographic printing. Its object is to produce economical and durablelithographic plates of a character capable of reproducing fine work.

The Zinc-plate is first cleaned with a suitable acid cleaning mixtureand is then grained by any means suitable to produce a fine grain on theplate and is then washed and dried. The plate is then coated with a suitable sensitizer, such as a solution of acetic acid and alum, and afterdrying is ready for the reception of a transfer or of a lithographicdrawing.

If a transfer is employed, it is properly applied to the plate and inthe usual manner the paper is soaked off, the plate is dried, and iscoated with a solution of gumarabic and dried again. The gum-arabicprotects the surface of the plate except over the greasy transfer-ink.Then an asphaltum etchingground is applied to the whole surface of theplate and is spread thereon by a soft cloth. This etching-groundreplaces the transfer-ink and is also spread over the surface of thegum-arabic. Then the plate is washed with water, whereby the gum-arabicis dissolved and is removed from the plate, together with theetching-ground lying upon it. The plate is then dampened and is rolledup with greasy lithographic ink and is powdered in the usual way with anetching-powder. The greasy ink clings to the etching-ground, which liesupon the surface originally cov ered by the transfer-ink, and theetchingpowder clings to the greasy lithographic ink. The plate duringall the time subsequent to the application of the etching-ground iskeptmoist in order that the lithographic ink shall be repelled from allparts thereof except those parts originally occupied by the lines of thetransfer. Next the p ate' is etched in a moving bath with the etchingand surfacing fluid described below. This etching is con ducted for asuitable length of time, which must be judged by the lithographer, andthus a surface is produced on the plate outside of the original linesoccupied by the transfer, which surface absorbs and retains a film ofwater. Then the plate is washed free from acids and is coated again witha solution of gum-arabic in water, which clings to the plate, exceptover the portions coated by the lithographic ink. The gum-arabic isdried, and then the etching-ground is spread a second time over theplate with a soft cloth, and the plate is ready for printing.

A suitable prepared asphalt etching-ground for the purposes abovementioned is a commercial article and is composed of soap, rosin,asphaltum, turpentine, and sometimes a little lavender-oil.

The etching and surfacing fluid above mentioned is ordinarily composedof one dram of muriatic acid, two drams of acetic acid,

(strongest commercial,) one-half ounce of plrimacid, one-quarter ounceof hos horic acid and one-half dram of powc ered copperas in about agallon of water. These proportions may be varied .within reasonablelimits. Where the etching must be rapid, the proportion of copperas isincreased, and where the etching is to be slow the proportion ofcopperas is decreased, or that ingredient is omitted entirely. Where adrawing is made upon the prepared zinc with the lithographic ink calledtuschflg. or with lithographic crayons, about twenty-four ounces ofgum-arabic are added to the abovementioned etching and surfacing fluid.This etching and surfacing fluid used in the manner above statedproduces a lithographic plate which is not intended or suitable for usein place of a wood cut or engraving, but is truly a lithographic plateand requires the employment of a film of water clinging to the absorbentsurface above mentioned, whereby lithographic ink is repelled therefromand clings only to the portions of the plate from which the saidabsorbent surface is absent. The surface produced by the above mixturein substantially the proportions above stated is exceedingly durable,hard, delicate in grain, and absorbent of water, whereby a zinc platemay be employed for many times the number of lithographic impressionswhich heretofore have been successfully printed from Zinc lithographiclates.

Any lithographic p otographer will employ a photographic method with azinc plate without further instruction, as the film of chromatedmaterial becomes insoluble under those parts of the negative thattransmit light, which are those parts of the negative that must bereproduced in black. The remainder of the material remains insoluble andcan be Washed ofi. The insoluble material therefore takes the place ofthe transfer in the initial stages of the process above described. Afterthe soluble material is removed the process continues as abovedescribed.

What I claim is 1. The process of producing lithographic zinc lates,consisting in producing a Water absor bent and retaining surface thereonoutside of the printing surface or lines by acting upon said plate by amineral-acid solution in combination with phosphoric and acetic acids.

2. The process of producing lithographic zinc lates, consisting inproducing a Water absor bent and retaining surface thereon outside ofthe printing surface or lines by acting upon said plate by amineral-acid solution in combination with phosphoric and acetic acidsand copperas.

3. The process of producing lithographic Zinc plates, consisting inproducing a Water absorbent and retaining surface thereon outside of theprinting surface or lines by acting upon said plate by a mineral-acidsolution in combination With muriatic and nitric acids, phosphoric andacetic acids, substantially in the proportions above set forth.

4. The process of producing lithographic zinc plates, consisting inproducing a Water absorbent and retaining surface thereon outside of theprinting surface or lines by acting upon said plate by a mineral-acidsolution in combination With muri-ati'c and nitric acids, phosphoric andacetic acids and copperas, substantially in the proportions above setforth.

CHARLES G. MEYN.

Witnesses D. GURNEE, J. C. MEYN.

